Rotary cutting head with fluid supply ducting

ABSTRACT

A rotary cutting head for a cutting machine having a plurality of nozzles positioned at a peripheral portion of the head to direct a fluid jet to a selection of cutting buttons located at cutter discs. The nozzles are positionally mounted at the head so as to direct the fluid jets to a radially outermost selection of the buttons during cutting.

FIELD OF INVENTION

The present invention relates to a rotary cutting head for a cuttingmachine and in particular, although not exclusively, to a cutting headadapted to provide a flow of a fluid to a set of spray nozzles mountedat a peripheral portion of the cutting head, that in turn produce fluidjets to a peripheral cutting region of the head.

BACKGROUND ART

A variety of different types of cutting machine have been developed forthe many different applications of rock cutting in a mine environmentsuch as cutting drifts, tunnels, subterranean roadways and the like.Undercutting machines are typically suitable for cutting hard rock byutilising an undercutting principle in which rotatable cutters areforced and dragged against the rock to create a groove that facilitatesovercoming the rock tensile strength.

Typically, an undercutting machine comprises a set of roller cuttersmounted at a cutting head that may be raised upward in the undercuttingmode. Each roller cutter comprises a cutter ring or disc rotatablymounted at a support shaft that is capable of rotation about its centralaxis. The cutter rings are wear parts and require interchange at regularintervals as they become worn under the aggressive contact with the hardrock.

Existing mining and excavation machines are typically provided with awater spraying mechanism that involves a continuous or intermittentsupply of water towards the cutting region to firstly cool the cuttingteeth and secondly assist with dust suppression. U.S. Pat. No. 3,563,324discloses a rotary cutting machine having a plurality of cutting teethmounted at a periphery of a cutter body. A plurality of atomisingnozzles are mounted at the cutter body so as to direct a jets of watertowards cutting teeth when cutting into the rock. Similarly, U.S. Pat.No. 4,296,824 discloses a set of nozzles mounted towards the cuttingregion of a cutter head to provide a continuous stream to the cuttingzone that entrains the cuttings rearwardly away from the cutting zone.U.S. Pat. No. 4,721,341 discloses a cutting head having an internallyfed spraying means in which water is fed at high pressure to a set ofspray nozzles positioned adjacent to the cutting teeth.

However, existing arrangements are disadvantageous for a number ofreasons. In particular, accelerated teeth wear and inefficient cuttingtypically result from a non-optimised supply of fluid (i.e. water) tothe teeth and the region of rock that is being cut. Effectively, thecutting teeth (alternatively referred to as cutting picks or buttons) inaddition to cutting new rock, grind already cut rock to smaller fineswhich is undesirable. Additionally, existing arrangements typicallyinvolve a complex fluid supply necessitating multiple sealed movinginterfaces, valves and the like that increase servicing and maintenanceand the risk of fluid leakage. Additionally, nozzles of existingarrangements can be susceptible to blockage from the dust and debrisproduced when cutting.

Accordingly, what is required is a cutting head that addresses theseproblems.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a rotary cuttinghead for a cutting machine adapted for an efficient cutting action andto minimise accelerated wear of cutting teeth (cutting picks or buttons)due to undesirable regrinding of already cut rock. It is a specificobjective of the present invention to provide and direct a flow of afluid into the path of the cutting edges or teeth so as to provide apurging or cleaning of the cutting region in addition to providingcooling of the cutting edges or teeth.

It is a further objective of the present invention to provide a simple,robust and reliable system to supply a (cleaning/cooling) fluid to acutting region of a rotary cutting head so as to minimise servicing,maintenance and the risk of fluid leakage. It is a yet further objectiveto minimise the number of component parts of the cutting head and inparticular the fluid supply system to effectively reduce the requirementfor and reliance on seals and valves at one or moving interfaces.

It is further objective to provide a fluid supply arrangement in whichspray nozzles at the cutting region are effective to provide anintermittent selective fluid supply to the cutting edges or teeth whilstbeing positionally located to minimise the risk of blockage or damage tothe nozzles during cutting. It is a further specific objective toprovide a rotary cutting head having a plurality of cutting units thatthemselves or the component parts of which are convenient to interchangefor servicing and maintenance purposes whilst minimising disruption toany sealed interfaces.

The above objectives are achieved via a rotary drill head in which arotatable support frame mounts a plurality of peripheral cutter units(each with a cutter disc optionally carrying cutting buttons) and havingat least a first set of spray nozzles positionally mounted at thesupport frame adjacent to each cutter unit so as to direct a fluid jetto a radially outer region of each of the discs (located radiallyoutside a peripheral portion of the support frame) that define aradially outermost perimeter of the cutting head. In particular, thenozzles of at least the first set are positioned so as to direct a fluidjet into the rotating path of selected cutter discs and in particularinto the region of a cut groove (formed into the rock by the cuttingaction of the head) at the very region radially outermost cuttingportions (selections) of the discs that are effective to cut the rock.This fluid spray is effective primarily to flush fines from around theregion of those active cutting regions (i.e. edges or buttons) so as toavoid regrinding of cut rock, and in turn maximise cutting efficiencyand minimise button wear. By positioning the nozzles at the rotatablesupport frame and not at the cutter units (and in particular the cuttingdiscs), the nozzles are better shielded from abrasive contact with therock during cutting.

Additionally, the fluid supply pathway (via internal ducting) does notextend through the independently rotatable cutting discs and thereforethe number of sealed moving interfaces (that form part of the fluidsupply pathway within the rotatable support frame) is minimised. Inturn, the present rotary cutting head minimises a requirement for seals,gaskets and the like so as to provide a simple, reliable and robustconstruction. The present rotary cutting head therefore is adapted forminimised servicing and maintenance together with providing a reducedrisk of fluid leakage. As will be appreciated, the nozzles of the firstset are also effective to provide cooling of the edges or buttons whichis advantageous to minimise operating temperatures and extend theoperational service lifetime of the discs.

The present rotary cutting head is further adapted to provide aselective fluid supply to selection of the cutter units in that not allcutter units are supplied with fluid at any one time and only thosecutter units having cutting discs that are active (i.e., cutting)receive the fluid. Additionally, the present invention via the specificpositioning of the nozzles directs the fluid jet to a selection orregion only of the cutting edges or buttons (at those selected cuttingdiscs) to further optimise the volume of fluid delivered to the cuttingregion and further enhance the efficiency of the cutting and fluidcleaning and cooling processes.

Additionally, the present rotary cutting head is adaptable to provide anintermittent supply of fluid via fluid delivery arrangements comprisingducts, slots, holes or bores that minimise a requirement for sealinginterfaces (between moving parts of the rotary cutting head).

According to a first aspect of the present invention there is provided arotary cutting head for a cutting machine comprising: a rotatablesupport frame having a radially inner region and a radially peripheralportion and being rotatably coupled to a rotation drive unit; aplurality of cutter units mounted at or towards the peripheral portion,each of the units having a cutter disc rotatably mounted at a cutterhub, a radially outer portion of each of the discs by rotation of thediscs configured to abrade rock and create a cut groove therein; each ofthe discs being rotatable relative to the rotatable support frame viaeach respective hub; a plurality of fluid supply ducts extending at thesupport frame and provided in fluid communication with a first set ofnozzles to deliver a fluid to the discs; the nozzles mounted at thesupport frame so that the discs are capable of independent rotationrelative to the nozzles; and the nozzles positionally mounted to directa fluid jet to a region of the discs that are located radially outsideof the peripheral portion of the support frame and that define aradially outermost perimeter of the cutting head.

Optionally, the cutting head further comprises a fluid flow director todirect a flow of fluid to a selection only of the nozzles at theperipheral portion of the support frame. Optionally, the fluid flowdirector is configured to provide fluid flow to a selection of thenozzles where the selection of nozzles includes nozzles positioned atthe support frame within an angular segment of 100° to 200°, 130° to170° or 140° to 160°. Such an arrangement is advantageous to minimise avolume of fluid utilised for the cleaning and cooling function at thecutting region and to avoid flooding of the cutting region.

Optionally, the fluid flow director comprises a disc located at theradially inner region of the support frame having a plurality of holesand/or slots extending over an angular segment of the disc in a range100° to 200°, 130° to 170° or 140° to 160°. Such an arrangement isadvantageous over alternative valve based arrangements that necessitatemultiple sealed interfaces. Accordingly, the present arrangement isbeneficial to minimise the number of component parts and to provide areliable assembly that is convenient to manufacture, install andmaintain.

Optionally, the cutting head comprises a fluid flow interrupter toprovide an intermittent fluid flow to the nozzles. Optionally, the fluidflow interrupter comprises a disc located at the radially inner regionof the support frame. Preferably the interrupter is configured tomanipulate a fluid flow to provide a pulsed fluid flow to the nozzlesaccording to predetermined timing intervals.

Preferably, the fluid supply ducts extend internally within the supportframe in a direction radially outward from the inner region to theperipheral portion. Preferably, the entire length of the fluid supplyducts are mounted internally in the cutting head. Optionally, the ductsinclude bores, channels or conduits formed as bores extending withinsolid components. Optionally, the fluid supply ducts may comprisetubing, hosing or other supply conduits mounted internally within thecutting head between external surfaces of the cutting head. Such anarrangement is advantageous to avoid damage to the supply ducts duringcutting as the cutting machine is operational in a confined environmentwhere contact with rock or other apparatus or machinery may damage thesupply ducts.

Preferably, the cutting head further comprises a second set of nozzlesin fluid communication with the fluid supply ducts and mounted at thesupport frame at respective positions to direct a fluid jet onto thehubs. Such an arrangement is advantageous to provide a cooling flow offluid to the nubs so as to effectively cool internal components of thecutter units including in particular oil, grease, bearings and the like.

Optionally, the first set and the second set of nozzles are mounted atrespective shrouds located at the peripheral portion of the supportframe and positioned between each of the hubs in a circumferentialdirection. Optionally, each nozzle of the first set is positioned ateach shroud at a position radially outside of each nozzle of the secondset. Such an arrangement is advantageous to minimise the length of spraycreated by the nozzles when delivered to the cutting edges or buttons(in a forward direction) and the hubs (in a rearward direction). Assuch, the present invention is advantageous to maximise efficiency ofthe use of a cleaning and cooling fluid and to avoid wastage andflooding of the cutting region.

Optionally, each shroud is detachably mountable at the support frame.Accordingly, each shroud may be conveniently detached and reattached atthe support frame if cleaning or other maintenance of the nozzles isrequired without disrupting the cutting units and remaining componentsof the cutting head.

Optionally, each disc is not independently rotatably driven relative tothe drive unit that drives rotation of the support frame. Preferably,each disc is configured to be rotatably driven exclusively via rotationof the support frame by the drive unit. Accordingly, the present cuttinghead is beneficial to provide an effective cutting action whilstminimising the drive components, the weight of the cutting machine andthe servicing and maintenance of the cutting head. Preferably, thecutting head further comprises a gear box arrangement having a driveshaft, the support frame rotatably mounted and driven via the driveshaft.

Optionally, the cutting head may comprise in the range 5 to 20 cutterunits mounted at the peripheral portion. Preferably, each of the cutterunits are identical including the corresponding cutter discs and hubs.

Optionally, the cutting head may comprise a plurality of cutting buttonsmounted at the radially outer portion of each of the discs, the nozzlespositionally mounted to direct the fluid jet to a selection of thebuttons of the discs that are located radially outside of the peripheralportion of the support frame that define the radially outermostperimeter of the cutting head. Preferably, the cutting buttons comprisea first material and the cutter discs comprise a second material, thematerial of the cutting buttons being harder than the material of thediscs.

Optionally, a rotational axis of each of the respective discs is alignedgenerally with the rotational axis of the support frame. Preferably,each rotational axis of each cutter disc is aligned approximatelyparallel with the rotational axis of the support frame. Optionally, eachrotational axis of each cutter discs is aligned to be inclined radiallyoutwardly from the rotational axis of the support frame at an angle inthe range 1 to 15°.

According to a further aspect of the present invention there is provideda cutting machine comprising at least one cutting head as claimedherein. Optionally, the cutting machine is an undercutting miningmachine, a continuous mining machine, an electrically operated miningmachine and/or a mining machine having one, two, three, four or morecutting heads mounted at distal ends of booms or arms capable ofpivoting movement relative to a main body or chassis of the machine.Optionally, the machine may comprise a fluid reservoir, fluid pump,supply hoses and valves to provide a source of a fluid to the cuttingheads.

BRIEF DESCRIPTION OF DRAWINGS

A specific implementation of the present invention will now bedescribed, by way of example only, and with reference to theaccompanying drawings in which:

FIG. 1 is a perspective view of a mobile undercutting mining machinesuitable for creating tunnels and subterranean roadways having a pair offorward mounted pivoting cutting arms each mounting a rotary cuttinghead according to one aspect of the present invention;

FIG. 2 is a underside view of one of the rotary cutting heads of FIG. 1with selected components removed for illustrative purposes in which aplurality of cutter units are mounted at a peripheral portion of arotatable support frame of the head according to a specificimplementation of the present invention;

FIG. 3 is a side elevation view of the cutting head of FIG. 2;

FIG. 4 is an underside perspective view of the rotary cutting head ofFIG. 2;

FIG. 5 is a magnified front view of a selection of the cutter units ofthe cutting head of FIG. 2 in which each unit comprises a hub thatmounts an independently rotatable cutting disc;

FIG. 6 is a magnified rear view of the selected cutting units of thecutting head of FIG. 2;

FIG. 7 is a cross-sectional view through A-A of the rotary cutting headof FIG. 2 having an internal fluid supply arrangement to deliver acleaning/cooling fluid to the cutting discs according to a specificimplementation of the present invention;

FIG. 8 is a perspective view of a shroud positioned adjacent to thecutting discs of the rotary head of FIG. 2 that mounts respectively afirst and a second spray nozzle to direct a fluid jet onto a region of acutting disc and a support hub of the rotary head of FIG. 2;

FIG. 9 is a cross-sectional view through B-B of the shroud of FIG. 8;

FIG. 10 is a front end view of the shroud of FIG. 8;

FIG. 11 is a rear end view of the shroud of FIG. 8; and

FIG. 12 is a plan view of a fluid director disc mountable at a radiallyinner region of the rotary cutting head of FIG. 2 to provide a selectivefluid supply to the cutting discs.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION

A fluid (e.g., water) supply system according to the present inventionis capable of delivering a fluid to a cutting region of a rotary cuttinghead mountable to a variety of different types of cutting or miningmachines. A specific implementation of a rotary cutting head inaccordance with the present invention is described with reference to anundercutting mining machine for creating tunnels and subterraneanroadways as a plurality of rotating heads are slewed laterally outwardand raised in the upward and downward direction during forward cutting.The rotary cutting head is adapted specifically to deliver a fluid tothe cutting region of the head so as to enhance cutting efficiency andreduce the rate of wear of cutting edges or teeth formed at a peripheralportion of the cutting head.

Referring to FIG. 1, a cutting machine 10 is configured to cut into rockwithin a mining environment to create drifts, subterranean roadways andthe like so as to form an underground mine network. Machine 10 isconfigured for operation in an undercutting mode in which a plurality ofrotatable roller cutter units 13 may be forced into the rock to create agroove or channel and then to be pivoted vertically upward so as toovercome the reduced tensile force immediately above the channel andbreak the rock. Accordingly, the cutting machine 10 is optimised forforward advancement into the rock using less force and energy typicallyrequired for conventional compression type cutters that utilise cuttingbits or picks mounted at rotatable heads.

Machine 10 comprises a main frame 11 a (or chassis) that mounts a sled11 b capable of sliding forward and aft along a forward region of thesled 11 a. A pair of support arms 12 are mounted at a forward region ofsled 11 b and are configured with parts to pivot independently via agenerally horizontal pivot axis and a generally vertical pivot axis. Arespective rotary cutting head 15 is mounted at the distal end of eacharm 12 and by rotation about the respective horizontal and verticalpivot axes is capable of being raised in a vertical plane (up and down)and to be slewed laterally in a horizontal plane (side-to-side). Eachcutting head 15 mounts a plurality of cutter units 13, with each unit 13rotatably mounting a respective cutter disc 14 (otherwise referred to asa roller cutter or cutting ring). As will be appreciated, machine 10further comprises additional components associated with conventionalundercutting apparatus including in particular an electric motor,jacking legs, tracks etc. The lateral slewing movement of each arm 12 isprovided by selective actuation of a first pair of externally mountedhydraulic cylinders 16, 17 and an internally mounted hydraulic cylinder18, with each of the three cylinders being configured to control one ofthe two arms via linear extension and refraction of the piston shafts aswill be appreciated.

Referring to FIGS. 2 to 4, each rotary cutting head 15, when viewed inplan (or at a cross section perpendicular to a rotational axis 24 of thehead 15) may be considered to be a wheel or disc having a radially innerregion 21 and a radially outer peripheral portion indicated generally byreference 20. Peripheral portion 20 is generally circular around axis24. Each head 15 comprises a support frame indicated generally byreference 23 that represents the main body of head 15. Support frame 23according to the specific implementation is a multi-component supportstructure comprising for example a series of panels, plates, struts,assemblies and attachment elements (i.e. bolts and/or screws) formedtogether as a unitary body to support the cutter units 13 and towithstand the significant loading forces encountered at the head 15during cutting.

As illustrated in FIGS. 2 and 4, the cutter units 13 are mounted at theperipheral portion 20 of support frame 23 to define generally a ring ofcutter units 13 extending around axis 24. The cutter units 13 aremounted at the peripheral portion 20 of frame 23 such that the outerregion of each cutter disc 14 extends radially beyond peripheral portion20. Accordingly, a diameter (or radius) of each head 15 is defined inpart by the radial outermost portion of each disc 14. In particular,each disc 14 carries a plurality of cutting buttons 19 (alternativelyreferred to as cutting picks or teeth) formed from a high abrasionresistant material as will be familiar to those skilled in the art.Buttons 19 project radially outward from a radially outer portion orperimeter of each disc 14. Accordingly, a region indicated generally byreference 28 of each of the discs 14 (and/or a selection of the buttons19) project radially beyond the peripheral portion 20 of support frame23. It is this region 28 (and selection of buttons 19) that representthe effective cutting portion of each cutter unit 13.

As will be understood, each of the discs 14 is mounted at a respectivecutter hub 25 that represents a majority component of each cutter unit13. Each hub 25 comprises internally mounted bearings to allow freerotation of each disc 14 about a rotational axis 26 extendinglongitudinally through each generally cylindrical hub 25. Each disc 14is not positively or power driven at each hub 25 but is in turn rotatedabout axis 26 (of each respective cutter unit 13) and central axis 24(of the respective cutting head 15) via the powered/driven rotation ofhead 15 by a drive unit 55 and gear box 22 as mounted at machine 10 andin particular each arm 12. That is, each head 15 is configured forrotation about axis 24 in direction R₁ so as to induce a correspondingrotation in direction R₂ of each disc 14 that is pressed in contact withthe rock during cutting. The region 28 of each disc 14 (i.e., selectionof cutting buttons 19) that extends radially beyond a radially outermostperipheral surface 27 of head 15 represent the ‘active’ cutting regionand buttons to provide the cutting action at any specific time period aseach disc rotates by direction R₂ and R₁ about each respective axis 26,24.

The peripheral portion 20 of each head 15 is defined by a plurality ofshrouds illustrated in isolation within FIGS. 8 to 11. Each shroud 40comprises a generally ‘hammer-head’ shaped main plate 42 from whichextends laterally a mounting flange 41 having through bores 43 toreceive attachment bolts to mount each shroud 40 at head support frame23. The shrouds 40 represent radially outermost components of each head15 and are positioned, in a circumferential direction, between eachrespective cutter unit 13 so to at least partially envelop or nestleagainst neighbouring cutter units 13 at a position immediately behindeach cutter disc 14. In particular, the ‘hammer-head’ shaped end of eachplate 42 is positioned in the axial direction (of axis 26) between disc14 and hub 25 such that laterally outward regions 42 a of a single plate42 are positioned immediately behind cutter disc 14 of two neighbouringcutter units 13. An end surface of plate 42 that extends between regions42 a represents the radially outermost surface 27 of the head 15 at thehead peripheral portion 20.

A recess portion 30 is indented into a first forward facing planarsurface 31 of plate 42. A first nozzle 29 is mounted internally withinplate 42 such that a spray tip of nozzle 29 is positioned at recessportion 30. Accordingly, with fluid supplied to nozzle 29, a fluid jetis capable of being directed from nozzle 29 forwardly and outwardly fromrecess portion 30 onto a part of a respective disc 14. A correspondingrecess portion 34 is formed within a second rearward facing planarsurface 32 of plate 42 with surface 32 orientated to be facing cutterhubs 25. A second nozzle 33 is mounted within plate 42 so as to have aspray tip that emerges within the recess portion 34 to be capable ofproducing a fluid jet in a rearward direction and outwardly from plate42. The forward facing first recess portion 30 and the first nozzle 29are positioned so as to be aligned along a direction (indicated by line52) transverse to a longitudinal axis 51 of plate 42 at an angle in arange 75 to 85°. Accordingly, each of the first nozzles 29 is orientatedso as to direct the fluid jet exclusively onto the region 28 (selectionof buttons 19) at the radially outermost region of head 15. Moreover,the nozzles 29 are positioned adjacent each disc 14 so as to direct thefluid jet onto the button selection 28 as each disc 14 rotates indirection R₂. That is, the spray jet from each nozzle 29 may beconsidered to flow in a clockwise direction whilst each disc 14 isconfigured to rotate in an anti-clockwise direction. With the head 15positioned against the rock during cutting, each nozzle 29 directs thefluid jet into the as-formed groove that is cut into the rock by thebutton selection 28 and in particular into the clearance space withinthe as-formed groove. This is beneficial to primarily flush the cutgroove and clear rock pieces and fines to avoid grinding and regrindingof the cut material.

Accordingly, the cutting efficiency of the present arrangement isenhanced. The position and configuration of each of the first nozzles 29also provides a secondary cooling of the buttons 19 and the peripheraledge of each disc 14 during cutting. This together with the flushing ofcut rock and fines minimises abrasive wear of the buttons 19 and discs14 so as to extend their service lifetime. In a direction of head axis24 (and a respective cutter unit axis 26), each nozzle 29 is positionedslightly axially rearward relative to each disc 14 and the buttons 19within the selection 28. As such, nozzles 29 and recess portions 30 arefurther orientated to be transverse to head axis 24 (and the respectivecutter unit axis 26) so as to direct the fluid jet axially forward ontothe buttons 19 within selection 28.

Each of the second nozzles 33 and respective second recess portions 34are aligned in a direction illustrated by line 58 that extendsperpendicular to the main length or axis 51 of plate 42. That is, eachsecond nozzle 33 is aligned transverse to each first nozzle 29 at eachplate 42 with an angle between the respective nozzles 29, 33 (as definedby directional lines 52, 58 respectively) being in a range 5 to 15°.Each of the second nozzles 33 and respective recess portions 34 arealigned in the direction of head axis 24 and cutter unit axis 26 to begenerally rearward facing at plate surface 32. Accordingly, the fluidjet produced from each nozzle 33 is directed rearwardly from surface 32and onto a cutter hub 25. Accordingly, each hub 25 is provided with acooling supply of fluid. Such an arrangement is advantageous to cool oiland grease internally within each hub 25 that in turn provides acontrolled cooling of the internal hub components (i.e., bearings etc.).

The fluid supply pathway to each of the first and second nozzles 29, 33will now be described with reference to FIGS. 7 to 12. Referringinitially to FIG. 7, cutting head support frame 23 comprises generally aforward facing annular face 37 and a rearward facing annular face 38. Acentral hub 35 is mounted at the radially inner portion 21 of head 15 torepresent an inner frame part of the head 15. A peripheral frameassembly 59 provides a radially outer region to which is mounted each ofthe cutter units 13 and shrouds 40. Each head 15 comprises internalducting extending radially between the inner hub 35 and outer assembly59. In particular, a central supply duct 57 (indicated schematically)provides a means of transferring fluid from a source reservoir into head15. Referring to FIG. 7 in combination with FIG. 12, a distributor disc60 is mounted at hub 35 to be centred on axis 24. Disc 60 comprises aseries of discreet holes or slots 63 that extend over an angulardistance towards a perimeter 62 of disc 60. According to the specificimplementation, disc 60 comprises eight slots extending between a firstendmost slot 63 a and a second endmost slot 63 b. An angle α between therespective end slots 63 a, 63 b is in a range 140 to 160°. Disc 60 ispositioned adjacent to central supply duct 57 via a central bossassembly 61 mounted at inner hub 35 such that fluid is capable offlowing from supply duct 57, through slots 63 and into ducting 36 viaport 45. Boss assembly 61 comprises a series of annular discs, platesand seals so as to securely mount disc 60 and provide a fluid tight sealfor the transfer of fluid into ducting 36 (within support frame 23).

Referring again to FIG. 7, hub 35 comprises a plurality of feed ductsillustrated generally by reference 36 that extend radially from hub 35to outer assembly 59. According to the specific implementation, eachhead 15 comprises a plurality of ducts 36 corresponding to the number ofcutter units 13, which according to the present embodiment, is 12. Eachfeed duct 36 comprises a radially inner receiving port 45 thatinterfaces with a respective disc slot 63 so as to allow a supply offluid from central supply duct 57 into feed duct 36. Fluid then flowsgenerally radially outward through feed duct sections 36 a, 36 b, 36 cand 36 e. Feed duct 36 further comprises various plugs 36 f, 36 drequired for manufacturing convenience. The feed supply of fluid emergesfrom head peripheral assembly 59 at supply port 46.

Referring to FIGS. 8 to 11, each shroud 40 comprises a fluid deliveryport 44 provided at rearward facing planar surface 32. A delivery duct48 extends axially within plate 42 being centred on axis 51 between port44 and a pair of outlet ports 49, 50. A first outlet port 49 is providedin fluid communication with second nozzle 33 and a second outlet port 50is provided in fluid communication with first nozzle 29, with the ports49, 50 being located toward one end of duct 48 and delivery port 44located towards an opposite end. Accordingly, fluid is capable of beingdelivered to the head central hub 35 and then to flow radially outwardthrough ducts 36 (via the distributed disc 60) and into each shroud 40to each respective nozzle 29, 33. Due to the angular arrangement of discslots 63, a selection only of cutter units 13 are supplied with fluid atany one time as head 15 rotates in direction R₁. Accordingly, aselection of the first and second nozzles 29, 33 are active to producerespective fluid jets onto the selections 28 of buttons 19 and cutterhubs 25 that are being used at that specific time instance when cuttingrock. In particular, the active cutter units 13 and accordingly firstand second nozzles 29, 33 include only those cutter units 13 arrangedover the same corresponding angular distance a relative to thedistributor slots 63.

According to aspects of the present invention, machine 10 and/or eachhead 15 may further comprise a fluid flow interrupter configured toprovide an intermittent flow of fluid to the nozzles 29, 33. Such aninterrupter may be implemented as a specifically configured disc mountedat the central boss in place of, or in addition to, disc 60. Thedistributor disc 60 (and optionally the fluid flow interrupter disc) arebeneficial to provide an efficient use of fluid to a selection only ofthe cutter units 13.

The above embodiment is described with reference to each of the discs 14having cutting buttons 19. According to further embodiments, each disc14 comprises a specifically configured radially outer perimeter edgeregion adapted to abrade rock (without the need for additional cuttingbuttons 19). According to such an embodiment, the first nozzles 29 areconfigured to direct a fluid jet to the cutting edge of each of thediscs 14.

1. A rotary cutting head for a cutting machine comprising: a rotatablesupport frame having a radially inner region and a radially peripheralportion and being rotatably coupled to a rotation drive unit; aplurality of cutter units mounted at or towards the peripheral portion,each of the plurality of units having a cutter disc rotatably mounted ata cutter hub, a radially outer portion of each of the discs by rotationof the discs being configured to abrade rock and create a cut groovetherein each of the discs being rotatable relative to the rotatablesupport frame via each respective hub; and a plurality of fluid supplyducts extending at the support frame and provided in fluid communicationwith a first set of nozzles to deliver a fluid to the discs, the firstset of nozzles being mounted at the support frame so that the discs arecapable of independent rotation relative to the nozzles, and wherein thenozzles are positionally mounted to direct a fluid jet to a region ofthe discs that are located radially outside of the peripheral portion ofthe support frame and that define a radially outermost perimeter of thecutting head.
 2. The cutting head as claimed in claim 1, furthercomprising a fluid flow director arranged to direct a flow of fluid to aselection only of the first set of nozzles at the peripheral portion ofthe support frame.
 3. The cutting head as claimed in claim 2, whereinthe selection of the first set of nozzles includes nozzles positioned atthe support frame within an angular segment of 100° to 200°, 130° to170° or 140° to 160°.
 4. The cutting head as claimed in claim 3, whereinthe fluid flow director includes a disc located at the radially innerregion of the support frame having a plurality of holes and/or slotsextending over an angular segment of the disc in a range 100° to 200°,130° to 170° or 140° to 160°.
 5. The cutting head as claimed in claim 1,further comprising a fluid flow interrupter arranged to provide anintermittent fluid flow to the first set of nozzles.
 6. The cutting headas claimed in claim 1, wherein the fluid supply ducts extend internallywithin the support frame in a direction radially outward from the innerregion to the peripheral portion.
 7. The cutting head as claimed inclaim 1, further comprising a second set of nozzles in fluidcommunication with the fluid supply ducts and mounted at the supportframe at respective positions to direct a fluid jet onto the hubs. 8.The cutting head as claimed in claim 7, wherein the first set and thesecond set of nozzles are mounted at respective shrouds located at theperipheral portion of the support frame and positioned between each ofthe hubs in a circumferential direction.
 9. The cutting head as claimedin claim 8, wherein each nozzle of the first set of nozzles ispositioned at each shroud at a position radially outside of each nozzleof the second set of nozzles.
 10. The cutting head as claimed in claim8, wherein each shroud 404 is detachably mountable at the support frame.11. The cutting head as claimed in claim 1, wherein each disc is notindependently rotatably driven relative to the drive unit that drivesrotation of the support frame.
 12. The cutting head as claimed in claim11, wherein each disc is configured to be rotatably driven exclusivelyvia rotation of the support frame by the drive unit.
 13. The cuttinghead as claimed in claim 1, further comprising a gear box arrangementhaving a drive shaft, the support frame being rotatably mounted anddriven via the drive shaft.
 14. The cutting head as claimed in claim 1,having in the range 5 to 20 cutter units mounted at the peripheralportion.
 15. The cutting head as claimed in claim 1, further comprisinga plurality of cutting buttons mounted at the radially outer portion ofeach of the discs, the first set of nozzles being positionally mountedto direct the fluid jet to a selection of the buttons of the discs thatare located radially outside of the peripheral portion of the supportframe that define the radially outermost perimeter of the cutting head.16. The cutting head as claimed in claim 1, wherein a rotational axis ofeach respective disc is aligned generally with the rotational axis ofthe support frame.
 17. A cutting machine 404 comprising at least onecutting head as claimed in claim
 1. 18. The cutting machine as claimedin claim 17, comprising an undercutting mining machine.